Rwanda has started a week of official mourning to mark the 20th anniversary of the country's genocide. Some 800,000 people were slaughtered in Rwanda by ethnic Hutu extremists. The questions many people are asking is: What led to such horrific events? And: How has Rwanda dealt with the aftermath, 20 years on? BBC Africa's Kassim Kayira, who is from Rwanda, answered your questions in a live Twitter Q&A on Monday 7 April.

This is an edited version of the session.

Question from @jweeraga: is Rwanda/ East Africa doing enough to stop such holocaust from ever happening again?

Kassim answers: Some mechanisms have been put in place but the fragility of many countries shows how easy it is to slide into chaos.

@AlekeMukunga: Who really shot down President's plane, triggering this holocaust?

Kassim: That's the million dollar question. There are several investigations that have been launched but none has been conclusive.

@kollybrado: How have successive governments attempted to mend fences in order for the nation to move on since the genocide? Have people's welfare improved?

Kassim: Well there's been only one government since but efforts have been made at empowering people and improving economic situation through sharing cows and loans.

Kassim: Also through improved healthcare all Rwandans have health insurance (mutuel de sante) malaria has been controlled to a huge extent.

Kassim: Plus international exposure which I think has changed if not impacted on people's mindsets and world outlook.

@jweeraga: The Gacaca courts, don't you think they breed more hatred than reconciliation?